Wireless power supply system based on magnetic coupling resonance and maximum efficiency point tracking method

Abstract

The application provides a wireless power supply system based on magnetic coupling resonance and a maximum efficiency point tracking method, and belongs to the field of wireless energy transmission, comprising a transmitting end and a receiving end; wherein the transmitting end comprises a power supply, a first microcontroller, a class-E power amplifier module, a current detection amplifier and an output adjustable DC-DC module; the receiving end comprises an input resonant circuit, a full-wave rectifier bridge circuit, a low-dropout linear regulator and a load connected in sequence. The receiving end of the application adopts a low-dropout linear regulator to realize linear regulation function of an equivalent load, avoiding the non-linear change of the equivalent load caused by the use of DC-DC. The maximum efficiency point tracking method is realized only by the output adjustable DC-DC of the transmitting end, compared with the design of double-side DC-DC control, reducing the loss caused by the circuit itself; the control method process is simpler than the PI control method of proportional and integral operation of the deviation between the given value and the actual value, saving the process of multiple comparison and adjustment, and further reducing the reaction time.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a wireless power supply system based on magnetic coupling resonance and a method for tracking the point of maximum efficiency. Background Technology

[0002] Wireless power transfer technology enables short-range, contactless power transmission, avoiding the issues of connecting wires and battery capacity inherent in traditional power supply methods. Due to its high flexibility, high safety, and high reliability, it has broad application prospects in implantable medical devices, wearable devices, and electric vehicles. Magnetic coupling resonance, as one method of wireless power transfer, achieves longer transmission distances and lower energy loss by setting the wireless power transmitter and receiver to the same resonant frequency, thus improving the overall efficiency of the wireless power supply system.

[0003] When the transmitting and receiving coils shift, the mutual inductance changes, leading to a decrease in the energy transfer efficiency of the wireless power supply system. For a given mutual inductance, there exists an optimal load or frequency point that maximizes the overall system efficiency. Maximum efficiency point tracking (MPPT) aims to adjust the receiver's load network accordingly when the system's mutual inductance changes, bringing it back to the optimal load or frequency point and improving system efficiency. Traditional control methods use DC-DC converters on both the transmitting and receiving sides to regulate the output voltage and maximize system efficiency, but this increases the overall complexity of the DC-DC converter, and the load change is non-linear. Therefore, a wireless power supply system with linearly adjustable receiver load needs to be designed. Based on this, a MPPT control method is proposed to improve the system's energy transfer efficiency. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, this invention provides a wireless power supply system based on magnetic coupling resonance and a method for tracking the maximum efficiency point.

[0005] To achieve the above objectives, the present invention provides a wireless power supply system based on magnetic coupling resonance, including a transmitter and a receiver.

[0006] The transmitting end includes a power supply, a first microcontroller and a Class E power amplifier module connected to the power supply, a current sensing amplifier connected between the first microcontroller and the Class E power amplifier module, and an output adjustable DC-DC module connected at both ends to the first microcontroller and the current sensing amplifier. The current sensing amplifier amplifies the input current into voltage proportionally through a sensing resistor. The first microcontroller collects the amplified voltage and converts it into a corresponding current value. The Class E power amplifier converts the DC power output from the output adjustable DC-DC module into electromagnetic energy and couples it to the receiving end.

[0007] The receiving end includes an input resonant circuit, a full-wave rectifier bridge circuit, a low-dropout linear regulator, and a load connected in sequence. A second microcontroller is connected between the full-wave rectifier bridge circuit and the low-dropout linear regulator. The second microcontroller acquires the input voltage of the low-dropout linear regulator and transmits it to the first microcontroller via wireless communication. The first microcontroller uses the acquired current and voltage data as feedback data for the control method, performs logical operations, and uses the calculation result as the output voltage of the transmitting end to control the wireless power supply system.

[0008] Preferably, the adjustable output DC-DC module includes a digital-to-analog converter and a DC-DC module connected in sequence. The adjustable output DC-DC module includes at least three resistors. The range and accuracy of the final output voltage are determined by controlling the value of each resistor. The calculation formulas for the output voltage and the current of each branch of the DC-DC module are as follows:

[0009]

[0010] Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter. FB This refers to the voltage at the FB pin of the DC-DC module.

[0011] Preferably, the Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit; one end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of the transistor Q1, and the drain and source of the transistor Q1 are connected to the output resonant circuit; the choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier; the output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiver.

[0012] Preferably, the maximum drain-source voltage of transistor Q1 is greater than or equal to 100V, the signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz, the choke inductor L is a power inductor greater than or equal to 68uH, and the output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC power.

[0013] Preferably, the receiving end adopts a low-dropout linear regulator structure, so that the equivalent load of the receiving end can be linearly adjusted by controlling the input voltage of the low-dropout linear regulator. The formula for calculating the equivalent load at the input of the low-dropout linear regulator is as follows:

[0014] R L ′=kR L ;

[0015] Among them, RL The actual load of the low-dropout linear regulator; k is the ratio of the input and output voltages of the low-dropout linear regulator; R L 'This is the equivalent load at the input of a low-dropout linear regulator.

[0016] Preferably, the input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected to both ends of the receiving coil L2, used to convert the received electromagnetic energy into high-frequency alternating current. The voltage received by the receiving coil L2 from the electromagnetic field is positively correlated with the mutual inductance between the transmitting current and the transmitting coil L1. The formula for calculating the voltage received by the receiving coil L2 is as follows:

[0017] V2=I1jwL m ;

[0018] Where V2 is the receiving coil voltage; I1 is the transmitting current; j is the imaginary unit; w is the resonant current angular frequency; L m This is mutual inductance between the coils.

[0019] Preferably, the resonant frequencies of both the output resonant circuit and the input resonant circuit are 13.56MHz.

[0020] Preferably, the current sensing amplifier is an INA190; the first microcontroller and the second microcontroller are both nRF52832; the full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end to end, and the unidirectional conducting elements are Schottky diodes.

[0021] This invention also provides a method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance, the tracking method comprising the following steps:

[0022] S1: After the receiver starts working, the second microcontroller collects the input voltage of the low dropout linear regulator and uploads it to the transmitter via wireless communication.

[0023] S2: After receiving the data transmitted from the receiver, the first microcontroller at the transmitter calculates the equivalent load of the mutual inductance, the parallel capacitor at the receiver, and the target equivalent load corresponding to the mutual inductance value based on the input voltage of the low dropout linear regulator and the current at the transmitter.

[0024] S3: Calculate the ratio of the input voltage to the output voltage of the low-dropout linear regulator required to make the equivalent load of the parallel capacitor at the receiving end equal to the target equivalent load;

[0025] S4: Calculate the current required at the transmitter to adjust the input voltage of the low-dropout linear regulator at the receiver to the result calculated in step S3;

[0026] S5: The first microcontroller at the transmitter adjusts the output voltage of the DC-DC module so that the transmitter current is equal to the result calculated in step S4, thereby achieving maximum efficiency point tracking.

[0027] Preferably, in step S2, the calculation formulas for the equivalent load of the mutual inductance, the parallel capacitor at the receiving end, and the target equivalent load are as follows:

[0028]

[0029] Where 'a' is the ratio of the peak AC voltage of the receiving coil to the DC voltage of the low-dropout linear regulator; 'w' is the resonant angular frequency of the wireless power supply system; I 10 1. The transmitter current before the DC-DC converter changes; 2. k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; 3. C is the value of the parallel capacitor at the receiver; 4. R L For the low-dropout linear regulator load; r1 is the internal resistance of the transmitting coil; r2 is the internal resistance of the receiving coil; V LDO This is the input voltage of the low-dropout linear regulator;

[0030] In step S3, the formula for calculating the ratio of the input voltage to the output voltage of the low-dropout linear regulator is as follows:

[0031]

[0032] Where k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; C is the parallel capacitance at the receiving end; R L R represents the load value of the low-dropout linear regulator. CRopt The adjusted target equivalent load;

[0033] In step 4, the formula for calculating the current magnitude is:

[0034]

[0035] Where k is the calculation result in step S3; a is the ratio of the peak value of the AC voltage of the receiving coil L2 to the DC voltage value of the front stage of the low dropout linear regulator; w is the resonant angular frequency of the wireless power supply system; L m The result of the calculation in step S2; V out This is the output voltage of the low dropout linear regulator;

[0036] In step S5, after the DC-DC module is adjusted by the first microcontroller, the formula for calculating its output voltage is as follows:

[0037]

[0038] Where V1 is the value after the DC-DC module changes; V 10I1 represents the value before the DC-DC module changes; I2 represents the calculation result in step four; I 10 The current at the transmitter before the change.

[0039] The advantages of the magnetically coupled resonant-based wireless power supply system and the method for tracking the maximum efficiency point provided by this invention are as follows: At the receiver end of the magnetically coupled resonant-based wireless power supply system, a low-dropout linear regulator is used to achieve linear adjustment of the equivalent load, avoiding the nonlinear changes in the equivalent load caused by using a DC-DC module, thus simplifying computational complexity. The method for tracking the maximum efficiency point is achieved solely through an adjustable DC-DC module at the transmitter end. Compared to designs involving dual-sided DC-DC control and auxiliary measurement coils, this simplifies the circuit structure and reduces losses inherent in the circuit itself. Furthermore, the control method is simpler than the PI control method, which performs proportional and integral calculations on the deviation between the given value and the actual value, eliminating multiple comparison and adjustment processes and resulting in a faster response speed. Attached Figure Description

[0040] Figure 1 Circuit diagram of a magnetically coupled wireless power supply system provided for this invention;

[0041] Figure 2 A schematic diagram of the adjustable DC-DC transmitter output provided by the present invention;

[0042] Figure 3 Equivalent circuit diagram of a wireless power supply system based on gyroscope theory provided for this invention;

[0043] Figure 4 The flowchart illustrates the steps of the method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance, as provided in this invention. Detailed Implementation

[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0046] In this embodiment of the invention, all directional indicators (such as up, down, left, right, front, back, lateral, longitudinal, etc.) are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0047] Due to installation errors and other reasons, the parallel relationship referred to in the embodiments of the present invention may actually be an approximate parallel relationship, and the perpendicular relationship may actually be an approximate perpendicular relationship.

[0048] like Figure 1 As shown, this invention provides a wireless power supply system based on magnetic coupling resonance, including a transmitter and a receiver. The transmitter includes a power supply, a first microcontroller and a Class E power amplifier module connected to the power supply, a current sensing amplifier connected between the first microcontroller and the Class E power amplifier module, and an output adjustable DC-DC module connected at both ends to the first microcontroller and the current sensing amplifier. The current sensing amplifier amplifies the input current into a voltage proportionally through a sensing resistor. The first microcontroller collects the amplified voltage and converts it into a corresponding current value. The Class E power amplifier converts the DC power output from the output adjustable DC-DC module into electromagnetic energy and couples it to the receiver. The receiver includes an input resonant circuit, a full-wave rectifier bridge circuit, a low-dropout linear regulator (LDO), and a load RL connected in sequence. A second microcontroller is connected between the full-wave rectifier bridge circuit and the low-dropout linear regulator (LDO). The second microcontroller acquires the input voltage of the low dropout linear regulator (LDO) and transmits it to the first microcontroller via wireless communication. The first microcontroller uses the acquired current and voltage data as algorithm input data, performs logical operations, and uses the calculation result as the output voltage of the transmitter to control the wireless power supply system.

[0049] Specifically, the Class E power amplifier module converts DC power into electromagnetic energy and transmits it to the receiver. The input resonant circuit at the receiver converts the received electromagnetic energy into high-frequency AC power, which is then output to a full-wave rectifier bridge circuit to convert the AC power back into DC power. Finally, a low-dropout linear regulator (LDO) converts this DC power to the required voltage level for the load R. L Power supply. The transmitting current is first amplified into voltage proportionally by the sensing resistor of the current sense amplifier. The receiving end's second controller acquires the input voltage data V of the low-dropout linear regulator (LDO) through its built-in successive approximation analog-to-digital converter (SAADC). LDO The voltage is converted into a corresponding current value and transmitted wirelessly to the transmitter as algorithm input data; the transmitter voltage can be obtained according to the conversion formula between the output voltage of the successive approximation analog-to-digital converter (SAADC) and the output voltage of the DC-DC module. The transmitter receives V... LDO The current coil mutual inductance L is calculated by combining the data with the transmitter current data.m And the optimal load value R corresponding to this mutual inductance CRopt Then, the voltage of the transmitter's DC-DC module is adjusted according to the control algorithm so that the transmitter current changes proportionally, thereby achieving maximum efficiency point tracking of the wireless power supply system.

[0050] In this embodiment, the input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected to both ends of the receiving coil L2, used to convert the received electromagnetic energy into high-frequency alternating current. The voltage received by the receiving coil L2 from the electromagnetic field is positively correlated with the mutual inductance between the transmitting current and the transmitting coil L1. The formula for calculating the voltage V2 received by the receiving coil L2 is as follows:

[0051] V2=I1jwL m ;

[0052] Where V2 is the voltage of the receiving coil L2; I1 is the transmitting current; and j is the imaginary unit (j 2 =-1); w is the angular frequency of the resonant current; L m This is mutual inductance between the coils.

[0053] In this embodiment, the receiving voltage V2 changes with the transmitting current I1, while the load current remains stable due to the presence of the LDO, so that the equivalent load of the receiving end changes linearly with V2, thus achieving maximum efficiency point tracking.

[0054] In this embodiment, both the first microcontroller in the transmitting end and the second microcontroller in the receiving end use Bluetooth chips of model nRF52832, and both ends use the 2.4GHz ESB communication protocol. The current sensing amplifier in the transmitting end is model INA190A2, which can collect and amplify the current of the output resonant circuit by 50 times; the DC-DC module uses a chip of model TPS61288, which has a wide output range of 4.5V-18V, meeting the voltage regulation range required by this invention.

[0055] In this embodiment, the Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit. One end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of transistor Q1. The drain and source of transistor Q1 are connected to the output resonant circuit. The choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier. The output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiving terminal. The maximum drain-source voltage of transistor Q1 is greater than or equal to 100V, and the signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz. The choke inductor L is a power inductor with a capacity of 68uH or greater; this power inductor can be surface-mount or through-hole. The output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC current. Additionally, a parallel sensing resistor R is provided at the output terminal of the current sensing amplifier. sense The current sensing amplifier detects the current through the sensing resistor R. sense The voltage is used to obtain the current of the system circuit.

[0056] In this embodiment, the Class E power amplifier module uses EPC8010 power transistors manufactured using gallium nitride technology, which meet the switching speed requirements under 13.56MHz operating conditions. The transistor driver uses an LTC6900 silicon oscillator chip.

[0057] like Figure 2 As shown, the adjustable output DC-DC module includes a digital-to-analog converter (DAC) and a DC-DC module connected in sequence. The power of the Class E power amplifier module is provided by the adjustable output DC-DC module. The adjustable output DC-DC module includes at least three resistors, preferably three, specifically resistors R1, R2, and R3. One end of resistor R2 is connected in series with resistor R1 and then grounded, while its other end is connected to the output voltage V of the DC-DC module. out One end of resistor R3 is connected to the diode and receives the output voltage V of the digital-to-analog converter (DAC). DAC The other end is connected between resistors R1 and R2 and to the FB pin of the DC-DC converter.

[0058] The adjustable DC-DC output module determines the range and accuracy of the final output voltage by controlling the value of each resistor. The 13.56MHz high-frequency AC output from the Class E power amplifier module converts electrical energy into electromagnetic energy through the transmitting coil L1; the 13.56MHz input resonant circuit, composed of the receiving coil L2 and the L-type impedance conversion network, converts the received electromagnetic energy into high-frequency AC and completes the impedance conversion function; the full-bridge rectifier and filter circuit completes the AC to DC conversion, and then the LDO completes the constant voltage power supply to the load.

[0059] The output voltage V of the DC-DC module out The formulas for calculating the current in each branch (the currents I1, I2, and I3 corresponding to resistors R1, R2, and R3) are as follows:

[0060]

[0061] Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter (DAC). FB This refers to the voltage at the FB pin of the DC-DC module.

[0062] The full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end-to-end, which are Schottky diodes. The preferred number of unidirectional conducting elements is four, and using Schottky diodes with lower forward voltage drop reduces circuit losses. However, if the wireless power supply system does not have high efficiency requirements, other diodes with unidirectional conducting function can be used instead. The specific device used can be replaced according to the actual application scenario.

[0063] In this embodiment, the resonant capacitors in the output resonant circuit include a parallel capacitor C and a series capacitor C1. The parallel capacitor C is connected in parallel with the drain and source of transistor Q1, and the series capacitor C1 is connected in series with the transmitting coil L1. The other end of the transmitting coil L1 is connected to one end of the source of transistor Q1. The parallel capacitor C and the series capacitor C1 are calculated using simulation software. By adjusting the values ​​of capacitors C and C1, the drain voltage waveform of transistor Q1 is made to an ideal waveform, achieving zero-voltage switching. The L-shaped impedance matching network in the input resonant circuit includes a parallel capacitor C2 and a series capacitor C3. The series capacitor C2 is connected in series with the receiving coil L2, and the parallel capacitor C3 is connected to the end furthest from the receiving coil L2 and is connected in parallel with the receiving coil L2. The load value transformed by the L-shaped impedance matching network should be within the range of the optimal equivalent load under different mutual inductance conditions of the receiving coil L2 to reduce the difficulty of tracking the maximum efficiency point. Furthermore, the resonant frequencies of both the output and input resonant circuits are 13.56MHz.

[0064] In this embodiment, the parameters of each component in the transmitting end are as follows: choke inductor L: 68uH; parallel capacitor C: 15pF; series capacitor C1: 85pF; transmitting coil L1: 2.25uH. The parameters of each component in the receiving end are as follows: receiving coil L2: 1.3uH; series capacitor C2: 330pF; parallel capacitor C3: 130pF.

[0065] Based on gyroscope theory, some components at the receiving end can be equivalent to a load, as shown in the specific equivalent circuit diagram below. Figure 3As shown. The full-wave rectifier bridge circuit, LDO, and load RF can be equivalently represented as the equivalent load R. L ', Equivalent load R L The parallel capacitor C3 can be equivalent to the equivalent load R of the parallel capacitor at the receiving end. CR The receiver employs a low-dropout linear regulator (LDO) structure, making the equivalent load R of the parallel capacitor at the receiver equal to the voltage across the receiver. CR Linear regulation can be achieved by controlling the LDO input voltage; the equivalent load R at the input of the low dropout linear regulator (LDO) is... L The formula for calculating ′ is as follows:

[0066] R L ′=kR L ;

[0067] Among them, R L The actual load of the LDO; k is the ratio of the LDO's input to its output voltage; R L 'This is the equivalent load at the input of the LDO.

[0068] In this embodiment, the power supply includes a first DC-DC power supply, a DC power supply, and a second DC-DC power supply connected in sequence. The first DC-DC power supply is connected to the microcontroller and supplies power to the microcontroller; the second DC-DC power supply is connected to the transistor driver chip in the Class E power amplifier module and supplies power to the transistor driver chip.

[0069] Specifically, the DC power supply is powered by a 3.7V lithium battery, which, after conversion by a first DC-DC power supply and a second DC-DC power supply, powers the microcontroller and the Class E power amplifier module. The first DC-DC power supply has an output voltage of 3.3V and is a TPS62840 chip, while the second DC-DC power supply has an output voltage of 5V and is a TPS61253 chip. In this embodiment, the models of the first DC-DC power supply, the second DC-DC power supply, and the power module are only one example; they can also be other DC-DC chips that meet the corresponding output voltage requirements. This invention does not limit the specific models used.

[0070] like Figure 4 As shown, the present invention also provides a tracking method for the maximum efficiency point of a magnetically coupled resonant wireless power supply system, used for controlling the aforementioned wireless power supply system. This method is implemented at the transmitting end and includes the following steps:

[0071] S1: After the receiver starts working, the second microcontroller collects the input voltage of the low dropout linear regulator (LDO) and uploads it to the transmitter via wireless communication;

[0072] Specifically, after the transmitter is powered on, the first microcontroller sets the output voltage of the DC-DC module to an initial value of 6V, and at the same time, the current sensing amplifier starts to detect changes in the transmitter current. After the receiver is powered on, the acquired LDO input voltage data is transmitted to the transmitter via wireless communication as feedback data for the control method. The initial setting value can be adjusted arbitrarily according to the operating voltage requirements of the receiver device.

[0073] S2: After receiving the data transmitted from the receiver, the second microcontroller at the transmitting end determines the LDO input voltage V. LDO The mutual inductance L is calculated from the transmitter current. m The equivalent load R of the parallel capacitor at the receiving end CR The target equivalent load R corresponding to the mutual inductance value CRopt Among them, mutual inductance L m The equivalent load R of the parallel capacitor at the receiving end CR Equivalent load R to the target CRopt The calculation formula is as follows:

[0074]

[0075] Where 'a' is the ratio of the peak AC voltage of the receiver coil to the DC voltage of the low-dropout linear regulator; 'w' is the resonant angular frequency of the wireless power supply system; I 10 1. The transmitter current before the DC-DC converter changes; 2. k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; 3. C is the value of the parallel capacitor at the receiver; 4. R L For the low-dropout linear regulator load; r1 is the internal resistance of the transmitting coil; r2 is the internal resistance of the receiving coil; V LDO This is the input voltage of the low-dropout linear regulator.

[0076] S3: Calculate the load that makes the parallel capacitor at the receiving end equal to the target equivalent load R. CRopt The required ratio k of the input voltage to the output voltage of the low-dropout linear regulator (LDO) to be regulated; where the formula for calculating this ratio k is as follows:

[0077]

[0078] Where k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; C is the parallel capacitance at the receiving end; R L R represents the load value of the low-dropout linear regulator. CRopt This is the adjusted target equivalent load.

[0079] S4: Calculate the current required at the transmitter to adjust the input voltage of the receiver's low-dropout linear regulator (LDO) to the value calculated in step S3; the formula for calculating the circuit size I1 is as follows:

[0080]

[0081] Where k is the calculation result in step S3; a is the ratio of the peak value of the AC voltage of the receiving coil L2 to the DC voltage value of the front stage of the low dropout linear regulator; w is the resonant angular frequency of the wireless power supply system; L m The result calculated in step S2; V out This is the output voltage of the low-dropout linear regulator.

[0082] S5: The first microcontroller at the transmitting end adjusts the output voltage of the DC-DC module so that the magnitude of the transmitting end current after adjustment is the result calculated in step S4, thereby completing the maximum efficiency point tracking. The formula for calculating the output voltage V1 of the DC-DC module after adjustment by the first microcontroller is:

[0083]

[0084] Where V1 is the value after the DC-DC module changes; V 10 I1 represents the value before the DC-DC module changes; I2 represents the calculation result in step four; I 10 The current at the transmitter before the change.

[0085] In summary, the magnetically coupled resonant wireless power supply system provided by this invention utilizes a low-dropout linear regulator at the receiver to achieve linear regulation of the equivalent load, avoiding the nonlinear changes in the equivalent load caused by using a DC-DC module and simplifying computational complexity. The method for tracking the maximum efficiency point of the magnetically coupled resonant wireless power supply system provided by this invention is implemented solely through an adjustable DC-DC module at the transmitter. Compared to designs involving dual-sided DC-DC control and auxiliary measurement coils, this simplifies the circuit structure and reduces losses inherent in the circuit itself. Furthermore, the control method is simpler than the PI control method, which performs proportional and integral calculations on the deviation between the given and actual values, eliminating multiple comparison and adjustment processes and resulting in a faster response speed.

[0086] Although the present invention has been disclosed above by way of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of protection claimed in the claims.

Claims

1. A method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance, characterized in that, A wireless power supply system based on magnetic coupling resonance includes a transmitter and a receiver; The transmitting end includes a power supply, a first microcontroller and a Class E power amplifier module connected to the power supply, a current sensing amplifier connected between the first microcontroller and the Class E power amplifier module, and an output adjustable DC-DC module connected at both ends to the first microcontroller and the current sensing amplifier. The current sensing amplifier amplifies the input current into voltage proportionally through a sensing resistor. The first microcontroller collects the amplified voltage and converts it into a corresponding current value. The Class E power amplifier converts the DC power output from the output adjustable DC-DC module into electromagnetic energy and couples it to the receiving end. The Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit; one end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of the transistor Q1, and the drain and source of the transistor Q1 are connected to the output resonant circuit. The choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier; the output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiving terminal. The receiving end includes an input resonant circuit, a full-wave rectifier bridge circuit, a low-dropout linear regulator, and a load connected in sequence. A second microcontroller is connected between the full-wave rectifier bridge circuit and the low-dropout linear regulator. The second microcontroller acquires the input voltage of the low-dropout linear regulator and transmits it to the first microcontroller via wireless communication. The first microcontroller uses the acquired current and voltage data as feedback data for the control method, performs logical operations, and uses the calculation result as the output voltage of the transmitting end to control the wireless power supply system. The tracking method includes the following steps: S1: After the receiver starts working, the second microcontroller collects the input voltage of the low dropout linear regulator and uploads it to the transmitter via wireless communication. S2: After receiving the data transmitted from the receiver, the first microcontroller at the transmitter calculates the equivalent load of the mutual inductance, the parallel capacitor at the receiver, and the target equivalent load corresponding to the mutual inductance value based on the input voltage of the low dropout linear regulator and the current at the transmitter. S3: Calculate the ratio of the input voltage to the output voltage of the low-dropout linear regulator required to make the equivalent load of the parallel capacitor at the receiving end equal to the target equivalent load; S4: Calculate the current required at the transmitter to adjust the input voltage of the low-dropout linear regulator at the receiver to the result calculated in step S3; S5: The first microcontroller at the transmitter adjusts the output voltage of the DC-DC module so that the transmitter current is equal to the result calculated in step S4, thereby achieving maximum efficiency point tracking.

2. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, The adjustable output DC-DC module includes a digital-to-analog converter and a DC-DC module connected in sequence. The adjustable output DC-DC module includes at least three resistors. The range and accuracy of the final output voltage are determined by controlling the value of each resistor. The calculation formulas for the output voltage and the current of each branch of the DC-DC module are as follows: ； Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter. FB This refers to the voltage at the FB pin of the DC-DC module.

3. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, The maximum drain-source voltage of the transistor Q1 is greater than or equal to 100V, and the signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz; the choke inductor L is a power inductor with a value greater than or equal to 68uH; the output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC power.

4. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, The receiving end employs a low-dropout linear regulator structure, allowing the equivalent load of the receiving end to be linearly adjusted by controlling the input voltage of the low-dropout linear regulator. The formula for calculating the equivalent load at the input of the low-dropout linear regulator is as follows: ; Among them, R L is the actual load of the low-dropout linear regulator; k is the ratio of the input and output voltages of the low-dropout linear regulator; This is the equivalent load at the input of a low-dropout linear regulator.

5. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, The input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected to both ends of the receiving coil L2, used to convert the received electromagnetic energy into high-frequency alternating current. The voltage received by the receiving coil L2 from the electromagnetic field is positively correlated with the mutual inductance between the transmitting current and the transmitting coil L1. The formula for calculating the voltage received by the receiving coil L2 is as follows: ; Where V2 is the receiving coil voltage; I1 is the transmitting current; j is the imaginary unit; w is the resonant current angular frequency; L m This is mutual inductance between the coils.

6. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1 or 5, characterized in that, The resonant frequencies of both the output resonant circuit and the input resonant circuit are 13.56MHz.

7. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, The current sensing amplifier is an INA190; the first and second microcontrollers are both nRF52832; the full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end-to-end, and the unidirectional conducting elements are Schottky diodes.

8. The method for tracking the maximum efficiency point of a wireless power supply system based on magnetic coupling resonance according to claim 1, characterized in that, In step S2, the calculation formulas for the equivalent load of mutual inductance, parallel capacitor at the receiving end, and target equivalent load are as follows: ； Where 'a' is the ratio of the peak AC voltage of the receiving coil to the DC voltage of the low-dropout linear regulator; 'w' is the resonant angular frequency of the wireless power supply system; I 10 1. The transmitter current before the DC-DC converter changes; 2. k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; 3. C is the value of the parallel capacitor at the receiver; 4. R L For the low-dropout linear regulator load; r1 is the internal resistance of the transmitting coil; r2 is the internal resistance of the receiving coil; V LDO This is the input voltage of the low-dropout linear regulator; In step S3, the formula for calculating the ratio of the input voltage to the output voltage of the low-dropout linear regulator is as follows: ； Where k is the ratio of the input voltage to the output voltage of the low-dropout linear regulator; C is the parallel capacitance at the receiving end; R L R represents the load value of the low-dropout linear regulator. CRopt The adjusted target equivalent load; In step 4, the formula for calculating the current magnitude is: ; Where k is the calculation result in step S3; a is the ratio of the peak value of the AC voltage of the receiving coil L2 to the DC voltage value of the front stage of the low dropout linear regulator; w is the resonant angular frequency of the wireless power supply system; L m This is the result calculated in Part Two; V out This is the output voltage of the low dropout linear regulator; In step S5, after the DC-DC module is adjusted by the first microcontroller, the formula for calculating its output voltage is as follows: ; Where V1 is the value after the DC-DC module changes; V 10 I represents the value before the DC-DC module changes; I1 represents the calculation result in step four; I 10 The current at the transmitter before the change.

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